1. Field of the Invention
The present invention relates to non-aqueous electrolyte secondary batteries, and more particularly to non-aqueous electrolyte secondary batteries having a current interrupting mechanism with excellent impact resistance.
2. Description of the Prior Art
In recent years, non-aqueous electrolyte secondary batteries have been used not only in compact devices such as mobile phones, notebook PCs, and digital cameras but also as the power source for driving electric vehicles and hybrid vehicles.
When used for the latter application, a plurality of batteries are connected in series to produce a high output. Non-aqueous electrolyte secondary batteries are made of highly reactive materials and therefore required to have a higher safety level than when used as the power source in the latter application than when used in compact devices. These secondary batteries are also required to have excellent impact and vibration resistance due to the characteristics of the application.
In attempts to improve battery safety, various examples of current interrupting mechanism have been proposed in Patent Documents 1 to 8 shown below to interrupt current flow when battery internal pressure increases.
Patent Document 1: Japanese Utility Model No. 04-24262
Patent Document 2: Japanese Patent Unexamined Publication No. 10-241653
Patent Document 3: Japanese Patent Unexamined Publication No. 08-171898
Patent Document 4: Japanese Patent Unexamined Publication No. 08-293301
Patent Document 5: Japanese Patent Unexamined Publication No. 09-55197
Patent Document 6: Japanese Patent Unexamined Publication No. 11-307080
Patent Document 7: Japanese Patent Unexamined Publication No. 11-154504
Patent Document 8: Japanese Patent Unexamined Publication No. 11-329405
These examples of current interrupting mechanism, however, are susceptible to malfunction due to vibration or impact.